Multi-dimensional signal encoding

ABSTRACT

Methods, systems, and apparatus, including computer programs encoded on a computer storage medium, for communicating signals using a multi-dimensional symbol constellation. In one example, a process for modulating a carrier signal includes the actions of mapping data to symbols of a multi-dimensional symbol constellation that includes at least three dimensions, each dimension of the constellation represented by a respective modulation signal. The dimensions of the constellation include first and second dimensions each of which are represented by respective in-phase modulation values and quadrature phase modulation values of a quadrature amplitude modulation (QAM) signal, and a third dimension represented by a transpositional modulation (TM) signal. The method further includes modulating a carrier signal with the TM signal and the QAM signal.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119 to U.S.Provisional Patent Application No. 62/530,568, filed Jul. 10, 2017,which is hereby incorporated by reference in its entirety.

BACKGROUND

Carrier modulation techniques are used to transmit information signalsfrom one location to another. Traditional signal modulation techniquesinclude, for example, amplitude modulation (AM), frequency modulation(FM), and phase modulation (PM). In addition, complex modulationtechniques exist that incorporate aspects of AM, FM, and PM such asquadrature phase shift keying (QPSK), amplitude phase shift keying(APSK) and including quadrature amplitude modulation (QAM).Transpositional Modulation, or TM is a type of modulation in whichinformation is conveyed by altering (e.g., transposing, time shifting) aharmonic of a carrier signal.

SUMMARY

This specification relates to methods and systems for encoding anddecoding communication signals for conducting electronic communicationsusing a combined traditional modulation and TM signal. Morespecifically, the specification relates to methods and systems forencoding and decoding a communication signal using a multi-dimensionalsymbol constellation whose coordinates are associated with a traditionalmodulation signal and a TM signal. Although discussed in the context ofTM, implementations of the present disclosure also may be applicable toidentifying other aspects or characteristics of various devices.

In a first aspect, the disclosure features a method of modulating acarrier signal that includes the actions of mapping data to symbols of amulti-dimensional symbol constellation that includes at least threedimensions, each dimension of the constellation represented by arespective modulation signal. The dimensions of the constellationinclude first and second dimensions each of which are represented byrespective in-phase modulation values and quadrature phase modulationvalues of a quadrature amplitude modulation (QAM) signal, and a thirddimension represented by a transpositional modulation (TM) signal. Themethod further includes modulating a carrier signal with the TM signaland the QAM signal. Other implementations of this aspect includecorresponding communication devices, systems, apparatus, andtransmitters configured to perform the actions of the method, andcomputer programs including instructions encoded on computer storagedevices to perform the actions of the method.

In a second aspect, the disclosure features a method of modulating acarrier signal that includes the actions of mapping bits of an inputdata stream to symbols of a multi-dimensional symbol constellation thatincludes at least three dimensions, symbol coordinates in two of the atleast three dimensions are represented by in-phase and quadrature phasecoordinates of a quadrature amplitude modulation (QAM) constellation andsymbol coordinates in a third dimension are represented by atranspositional modulation (TM) signal. The method further includesmodulating a carrier signal with the TM signal and with the in-phase andquadrature phase coordinates of the QAM signal. Other implementations ofthis aspect include corresponding communication devices, systems,apparatus, and transmitters configured to perform the actions of themethod, and computer programs including instructions encoded on computerstorage devices to perform the actions of the method.

In a third aspect, the disclosure features a method of modulating acarrier signal that includes the actions of mapping data to symbols of amulti-dimensional constellation that includes at least two dimensions,the symbols of the constellation are represented by a respective sets ofcoordinates that each include a first coordinate associated with anon-TM signal, and a second coordinate associated with a transpositionalmodulation (TM) signal. The method further includes modulating a carriersignal with the non-TM signal and the TM signal. Other implementationsof this aspect include corresponding communication devices systems,apparatus, and transmitters configured to perform the actions of themethod, and computer programs including instructions encoded on computerstorage devices to perform the actions of the method.

In a fourth aspect, the disclosure features a method of modulating acarrier signal that includes the actions of mapping data to symbols of amulti-dimensional constellation that includes at least three dimensions,the symbols of the constellation are represented by a respective sets ofcoordinates that each include a first coordinate associated with a firstsignal, a second coordinate associated with a second signal, and a thirdcoordinate associated with a third signal. At least one of the first,second, and third signal is a transpositional modulation (TM) signal.The method further includes modulating a carrier signal with the first,second, and third signals. Other implementations of this aspect includecorresponding communication devices, systems, apparatus, andtransmitters configured to perform the actions of the method, andcomputer programs including instructions encoded on computer storagedevices to perform the actions of the method.

These and other implementations can each optionally include one or moreof the following features. In some implementations, themulti-dimensional constellation includes four dimensions, where therespective sets of coordinates each further include a fourth coordinateassociated with a second TM signal, the first and second signals arerespective in-phase and quadrature-phase portions of a QAM signal andthe third signal is a first TM signal, and where modulating the carriersignal comprises modulating the carrier signal with the QAM signal, thefirst TM signal, and the second TM signal.

In some implementations, the multi-dimensional constellation includesfour dimensions, where the respective sets of coordinates each furtherinclude a fourth coordinate associated with one of a phase value or anamplitude value of the TM signal, and where the third coordinate of eachof the respective sets of coordinates is associated with the other oneof a phase value or an amplitude value of the TM signal.

In some implementations, the multi-dimensional symbol constellationincludes a plurality of layers of two-dimensional QAM constellations andmodulation values of the TM signal represent particular QAMconstellation layers.

In some implementations, the multi-dimensional symbol constellationincludes at least four layers of 16-ary QAM constellations.

In some implementations, the multi-dimensional symbol constellationincludes at least eight layers of 256-ary QAM constellations.

In some implementations, adjacent symbols in the multi-dimensionalconstellation are encoded using Gray coding.

In some implementations, the method includes encoding the data using anerror correction coding scheme before mapping the data to symbols of themulti-dimensional constellation.

In some implementations, the second coordinate of each of the respectivesets of coordinates is associated a phase value the TM signal and thethird coordinate of each of the respective sets of coordinates isassociated an amplitude value the TM signal.

In some implementations, the first signal is an amplitude modulationsignal, a frequency modulation signal, or a phase modulation signal.

In a fifth aspect, the disclosure features a method of demodulating acarrier signal that includes the actions of receiving a combined signalincluding a carrier signal modulated with a quadrature amplitudemodulated (QAM) signal and a transpositional modulated (TM) signal, thecombined signal encoding data in a multi-dimensional symbolconstellation that has at least three dimensions. Separating the TMsignal from the QAM signal. Demodulating the QAM signal to obtain firstand second coordinates of a symbol. Demodulating the TM signal to obtaina third coordinate of the symbol. Other implementations of this aspectinclude corresponding communication devices, systems, apparatus, andtransmitters configured to perform the actions of the method, andcomputer programs including instructions encoded on computer storagedevices to perform the actions of the method.

In a sixth aspect, the disclosure features a method of demodulating acarrier signal that includes the actions of receiving a combined signalincluding a carrier signal modulated with a quadrature amplitudemodulated (QAM) signal and a transpositional modulated (TM) signal, thecombined signal encoding digital data in a multi-dimensional symbolconstellation that has at least three dimensions. Separating the TMsignal from the QAM signal. Demodulating the QAM signal to obtain firstand second portions of the digital data. Demodulating the TM signal toobtain a third portion of the digital data. Other implementations ofthis aspect include corresponding communication devices, systems,apparatus, and transmitters configured to perform the actions of themethod, and computer programs including instructions encoded on computerstorage devices to perform the actions of the method.

These and other implementations can each optionally include one or moreof the following features.

In some implementations, the method includes mapping the first, second,and third coordinates of the symbol to a pattern of bits associated withthe symbol.

In some implementations, the TM signal is a first TM signal and thecarrier signal includes an in-phase portion modulated with the first TMsignal and a quadrature-phase portion modulated with the second TMsignal, and demodulating the TM signal includes demodulating the firstTM signal to obtain the third coordinate of the symbol, and demodulatingthe second TM signal to obtain a fourth coordinate of the symbol.

In some implementations, demodulating the TM signal includesdemodulating a phase value of the TM signal to obtain the thirdcoordinate of the symbol, and demodulating an amplitude value of the TMsignal to obtain a fourth coordinate of the symbol.

In some implementations, the multi-dimensional symbol constellationincludes a plurality of layers of two-dimensional QAM constellations andmodulation values of the TM signal represent particular QAMconstellation layers.

In some implementations, the multi-dimensional symbol constellationincludes at least four layers of 16-ary QAM constellations.

In some implementations, the multi-dimensional symbol constellationincludes at least eight layers of 256-ary QAM constellations.

In some implementations, adjacent symbols in the multi-dimensionalconstellation are encoded using Gray coding.

In a seventh aspect, the disclosure features a method of demodulating acarrier signal that includes the actions of receiving a combined signalincluding a carrier signal modulated with a transpositional modulated(TM) signal and a non-TM signal, the combined signal encoding digitaldata in a multi-dimensional symbol constellation. Separating the TMsignal from the non-TM signal. Demodulating the non-TM signal to obtaina first coordinate of a symbol. Demodulating the TM signal to obtain asecond coordinate of the symbol. Other implementations of this aspectinclude corresponding communication devices, systems, apparatus, andtransmitters configured to perform the actions of the method, andcomputer programs including instructions encoded on computer storagedevices to perform the actions of the method.

These and other implementations can each optionally include one or moreof the following features. In some implementations, the method includesmapping the first and second coordinates of the symbol to a pattern ofbits associated with the symbol.

In some implementations, the TM signal is a first TM signal and thecarrier signal includes an in-phase portion modulated with the first TMsignal and a quadrature-phase portion modulated with the second TMsignal, and demodulating the TM signal includes demodulating the firstTM signal to obtain the second coordinate of the symbol, anddemodulating the second TM signal to obtain a third coordinate of thesymbol.

In some implementations, demodulating the TM signal includesdemodulating a phase value of the TM signal to obtain the secondcoordinate of the symbol, and demodulating an amplitude value of the TMsignal to obtain a third coordinate of the symbol.

In some implementations, the multi-dimensional symbol constellationincludes a plurality of layers of two-dimensional QAM constellations andmodulation values of the TM signal represent particular QAMconstellation layers.

In some implementations, the multi-dimensional symbol constellationincludes at least four layers of 16-ary QAM constellations.

In some implementations, the multi-dimensional symbol constellationincludes at least eight layers of 256-ary QAM constellations.

In some implementations, adjacent symbols in the multi-dimensionalconstellation are encoded using Gray coding.

Particular implementations of the subject matter described in thisspecification can be implemented so as to realize one or more of thefollowing advantages. Implementations may permit the expansion of signalconstellations from two-dimensions (such as traditional QAMconstellations) to three or more dimensions, and thereby, increase thenumber of bits that can be represented by individual symbols of theconstellations. Implementations may increase the data rate of signalstransmitted using traditional modulation schemes. Implementations mayprovide higher rates of data transmission by utilizing additionaldimension(s) of the transmitted signal space to carry the additionalinformation. Implementations may increase the data throughput ofindividual wired or wireless data links.

The details of one or more implementations of the subject matterdescribed in this specification are set forth in the accompanyingdrawings and the description below. Other features, aspects, andadvantages of the subject matter will become apparent from thedescription, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an example system in accordance with implementations ofthe present disclosure.

FIG. 2 depicts a block diagram of an example transmitter in accordancewith implementations of the present disclosure.

FIG. 3 depicts a diagram of an exemplary multi-dimensional symbolconstellation in accordance with implementations of the presentdisclosure.

FIG. 4 depicts a block diagram of an example receiver in accordance withimplementations of the present disclosure.

FIG. 5 depicts example system that implements aspects of the presentdisclosure in the context of a mobile communication environment.

FIGS. 6 and 7 depict example processes that can be executed inaccordance with implementations of the present disclosure.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

Implementations of the present disclosure generally relate to methodsand systems for encoding data in multi-dimensional symbolconstellations. More specifically, the specification relates to methodsand systems for encoding and decoding a data signal using amulti-dimensional symbol constellation whose coordinates are associatedwith a traditional modulation signal and a transpositional modulating(TM) signal. Implementations of the present disclosure generally relateto methods and systems for encoding digital data by mapping the digitaldata to symbols of a multi-dimensional symbol constellation thatincludes three or more dimensions. Each dimension of the constellationis represented modulation values or levels of a modulation signal. Forexample, in a three-dimensional symbol constellation, symbol coordinatesin a first and second dimension can each be associated with respectivein-phase and quadrature-phase values of a non-TM signal such as aquadrature amplitude modulation (QAM) signal, and symbol coordinates ina third coordinate can be associated with a values of a TM signal. Eachsymbol of the constellation represents a set of bits (e.g., an N-bitbinary number) of the data signal, and is itself represented by a set ofcoordinates within the constellation. A carrier signals is modulatedwith the QAM and the TM signal.

As used herein the terms “Transpositional Modulation,” “TM modulation,”“TM,” and “TM signal” refer to techniques of adding information to acarrier signal without affecting the amplitude, frequency or phase ofthe carrier signal (or a signal that is modulated according to such atechnique) as observed by a traditional receiver or demodulator (e.g., anon-TM capable receiver/demodulator). Transpositional modulation can begenerated by several techniques. For example, in a “wide-band TMmodulation” technique information is conveyed by modulating theinflection points of a carrier wave to represent data. For example, in a“harmonic TM modulation” technique information is conveyed by altering(e.g., transposing, time shifting) a harmonic of a carrier signal. Forexample, Transpositional Modulation can be produced by altering a thirdharmonic or other harmonics of a carrier signal (e.g., a fourthharmonic, fifth harmonic, sixth harmonic, etc.). For example, in an“internal TM modulation” technique information is conveyed by altering aperiodic signal (an “internal TM modulation signal”) which is applied tothe carrier signal. Any effects of the TM internal modulation signal oneither the carrier wave itself or another traditional modulation signal(e.g., non-TM signal) carried by the carrier wave cancel over the symbolframe of a non-TM modulation signal, and consequently, are notdetectable by a traditional signal demodulator. Examples of documentsthat describe techniques for performing TM modulation and demodulationand/or uses of transpositional modulation include, but are not limitedto, U.S. Pat. No. 9,014,293 entitled “TRANSPOSITIONAL MODULATION SYSTEMSAND METHODS;” U.S. Pat. No. 9,338,041 entitled “EXTRACTING CARRIERSIGNALS FROM MODULATED SIGNALS;” U.S. Pat. No. 9,338,042 entitled“SEPARATING AND EXTRACTING MODULATED SIGNALS;” U.S. Pat. No. 9,473,983entitled “TRANSPOSITIONAL MODULATION COMMUNICATIONS BETWEEN DEVICES;”U.S. Pat. No. 9,515,815 entitled “TRANSPOSITIONAL MODULATION SYSTEMS,METHODS AND DEVICES;” U.S. Pat. No. 9,516,490 entitled “IDENTIFYINGDEVICES WITH TRANSPOSITIONAL MODULATION;” U.S. Pat. No. 9,628,318entitled “TRANSPOSITIONAL MODULATION COMMUNICATIONS;” and U.S. patentapplication Ser. No. 15/491,569 entitled “TRANSPOSITIONAL MODULATION.”TM signals generated by each of the above techniques share the samecharacteristics in that the TM signals add information to a carriersignal without affecting the amplitude, frequency or phase of thecarrier signal as observed by a traditional demodulator (e.g., non-TMdemodulator) and the TM signals are not detectable by traditionaldemodulators, for example, those used for amplitude, frequency, or phasemodulated signals.

FIG. 1 depicts an example system 100 in accordance with implementationsof the present disclosure. The system 100 is a system of communicationdevices 102 a, 102 b, and 102 c. The system 100 may be a radio frequency(RF) communication system, a satellite communication system, a landlinecommunication system (e.g., a telephony or cable network), an opticalcommunication system, a computer network, or any other system ofcommunication devices. The communication devices 102 include systems formodulating a carrier signal with an information signal using traditionalmodulation techniques and transmitting and receiving the modulatedsignal from one communication device 102 to/from another. For example,communication device 120 a may be a cellular base station, andcommunication devices 102 b and 102 c may be mobile devices (e.g.,smartphones).

Communication devices 102 a and 102 b include transmitters 104 formodulating a carrier signal with an information signal using bothtraditional modulation techniques (e.g., QAM) and TM techniques, andreceivers 106 for receiving both traditionally modulated and TM signals.More specifically, communication devices 102 a and 102 b include acombined QAM-TM transmitter 104 and a combined QAM-TM receiver 106.Communication device 102 c includes a transmitter 118 for modulating acarrier signal with an information signal using only traditionalmodulation techniques, and a receiver 120 for receiving traditionallymodulated signals (e.g., QAM signals). More specifically, communicationdevice 102 c includes a QAM transmitter 118 and a QAM receiver 120.Traditional modulation techniques include, for example, amplitudemodulation (AM), frequency modulation (FM), and phase modulation (PM) inaddition to complex modulation techniques that incorporate aspects ofAM, FM, and PM such as quadrature phase shift keying (QPSK), amplitudephase shift keying (APSK) and including quadrature amplitude modulation(QAM). The various transmitters 104, 118 and/or receivers 106, and 120can be implemented as hardware devices (e.g., integrated circuits,chip-sets, application specific integrated circuits (ASIC) or fieldprogrammable logic arrays (FPGA)) or they can be implemented in software(e.g., as a software defined radio (SDR)).

Communication devices 102 a and 102 b can transmit and receive signalsthat include non-TM (e.g., traditionally modulated) signals 108 combinedwith TM modulated signals 110 on the same carrier. The combined signal112 provides an increased data rate over either the non-TM signal 108 orTM signal 110 alone because the non-TM signal and TM signal aretransparent to each other. The QAM-TM receiver 106 can separate the TMsignal 110 from the combined signal and demodulate the TM signal 110.Likewise, QAM-TM receiver 106 can separately demodulate thetraditionally modulated signal 108 (e.g., QAM signal) with nosignificant interference caused by the TM modulated signal 110. This ispossible because TM modulated signals are undecipherable by non-TMreceivers, instead appearing as a slight increase of noise intraditionally modulated signals.

For example, communication device 102 a may transmit a combined QAM-TMsignal 112 to communication device 102 b. Communication device 102 b canthen receive the combined signal 112. The QAM-TM receiver 106 incommunication device 102 b is used to detect and demodulate the non-TMsignal 108, and to separate and demodulate the TM signal 110 from thecombined signal 112. On the other hand, communication device 102 c,which does not have a TM capable receiver, will only detect anddemodulate the traditionally modulated signal 108; not the TM modulatedsignal 110.

Systems and techniques for modulating and demodulating TM signals aredescribed in U.S. Patents and Patent Applications listed above. Morespecifically, U.S. Pat. Nos. 9,014,293 and 9,515,815 describe severalsystems and methods for producing and demodulating TM signals includingthe above noted “wide-band” and “harmonic” modulation techniques, amongothers. U.S. Pat. Nos. 9,014,293 and 9,515,815 are each incorporatedherein by reference in their entirety. U.S. Pat. No. 9,338,042 describessystems and methods for separating TM signals from combined signals aswell as TM modulation and demodulation using “harmonic” modulationtechniques. U.S. Pat. No. 9,338,042 is incorporated herein by referencein its entirety. U.S. patent application Ser. No. 15/491,569 describessystems and methods for producing and demodulating TM signals using theabove noted “internal TM modulation” technique. U.S. patent applicationSer. No. 15/491,569 is incorporated herein by reference in its entirety.

Transpositional modulation can be used to increase the overall datathroughput of communication systems, such as system 100, by using the TMsignal 110 as an additional communication layer of existing channels.For example, as described in U.S. Pat. Nos. 9,338,042; 9,473,983;9,515,815; 9,516,490; and U.S. Pat. No. 9,628,318, a TM signal 110 canbe added to a carrier signal along with a non-TM signal 108, and can beused to transmit an information stream separate from an informationstream carried by the non-TM signal 108. In other words, the TM signal110 can be used to carry an additional information stream that isindependent of an information stream carried by a non-TM signal 108 onthe same carrier. Accordingly, the TM signal 110 and non-TM signal 108in a combined signal 112 can be used to send different information toseparate receiving devices.

In some implementations, as disclosed herein, transpositional modulationcan be used to increase the data throughput of communication systems,such as system 100, by using the TM signal 110 to provide an expandedsymbol constellation for the non-TM signal 108, thereby, increasing theoverall data rate for transmitting a common information stream betweentwo communication devices. In other words, both the TM signal 110 andthe non-TM signal in a single combined signal 112 can be used to encodeportions of a common information signal. For purposes of illustration,techniques for encoding portions of a common information signal in a TMsignal and a non-TM signal are described in reference to TM and QAMsignals. In other implementations, however, multi-dimensional symbolconstellations can be represented by a combination of TM signals andnon-TM signals other than QAM.

FIG. 2 depicts a block diagram of an example signal transmitter 200 inaccordance with implementations of the present disclosure. Transmitter200 is a combined QAM-TM transmitter. Transmitter 200 can be implementedin hardware (e.g., as integrated circuits, chip-sets, applicationspecific integrated circuits (ASIC) or field programmable logic arrays(FPGA)) or in software (e.g., as a software defined radio (SDR)).Transmitter 200 includes a symbol mapper 204, a QAM modulator 206, a TMmodulator 208, and a signal combiner 214. In addition, transmitter 200,optionally, includes an encoder 202. Transmitter 200 can also includevarious filters and amplifiers (not shown) to properly condition signalsfor transmission.

Encoder 202 receives a data signal from an input data stream. Encoder202 can encode the input data for error detection/correction, encryptthe data, or both. For example, encoder 202 can apply an errorcorrection or error detection code to the input data. Such errorcorrection or detection codes can include, but are not limited to,parity bits, checksums, forward error correction codes, hashing, andcyclic redundancy checks. In some implementations, encoder 202 canencrypt the input data or add digital signatures to the data.

Symbol mapper 204 maps the input data to symbols in a multi-dimensionalsymbol constellation. For example, symbol mapper 204 maps sets of N bitsof the input data to data symbols an M-ary symbol constellation, whereM=2^(N). The multi-dimensional symbol constellation includes at leastthree dimensions, where individual symbols are represented by a set ofat least three coordinates; one coordinate in each dimension.Furthermore, each symbol represents a particular pattern of N bits ofthe input data (e.g., an N-bit binary number). Symbol coordinates are ofone or more of the dimensions are represented by modulation values of aQAM (e.g., non-TM signal) and symbol coordinates of one or more otherdimensions are represented by modulation values of a TM signal ormultiple TM signals.

For example, FIG. 3 illustrates a diagram of an exemplarymulti-dimensional symbol constellation 300. The constellation 300 is athree-dimensional, 64-ary constellation. Constellation 300 includes 64data symbols 302 that each represent a unique pattern of 6 bits. Eachsymbol 302 is represented by coordinates in each of the threeconstellation dimensions (X₁, X₂, and X₃). Symbol coordinates in eachdimension are, in turn, represented by modulation values of respectivemodulation signals.

For example, symbol coordinates in the X₁ dimension can be representedby modulation values of the real part (or in-phase part) of a QAM signal(QAM_({Re})), symbol coordinates in the X₂ dimension can be representedby modulation values of the imaginary part (or quadrature-phase part) ofthe QAM signal, and symbol coordinates in the X₃ dimension can berepresented by modulation values a TM signal (TM). The real andimaginary parts of the QAM signal are designated as QAM_({Re}) andQAM_({Im}), respectively. For example, an i-th symbol 302 may representthe bit patterns (011010b), and may itself be represented by a set ofmodulation values (X_(1,i), X_(2,i), X_(3,i)), whereX_(1,i)=QAM_({Re},i), X_(2,i)=QAM_({Im}i,), and X_(3,i)=TM_(i).

Referring again to FIG. 2, symbol mapper generates modulation signalsX₁, X₂, and X₃ to control QAM modulator 206 and TM modulator 208. QAMmodulator 206 generates the real and imaginary parts of a QAM signalbased on modulation signals X₁ and X₂. For example, QAM modulator 206can include two amplitude modulators 210, 212 that each modulaterespective in-phase and quadrature-phase channels of a carrier signal.TM modulator 208 generates a TM signal based on modulation signal X₃.

TM modulator 208 can, for example, generate the TM signal using“wide-band TM modulation” techniques, “harmonic TM modulation”techniques, or “internal TM modulation” techniques. For example, in“wide-band TM modulation” techniques data is encoded in the TM signal byvariations the location of inflection points of the carrier signal, asdescribed in U.S. Pat. No. 9,515,815 at col. 4:48-9:19, which isincorporated herein by reference. Using “wide-band TM modulation”techniques, for example, TM modulator 208 can generate TM signals whichrepresent X₃ dimension coordinates of constellation symbols 302 byvariations the location of inflection points of the carrier signal.

As another example, in “harmonic TM modulation” techniques data isencoded in time or phase shifts of a harmonic of the carrier signal,which is heterodyned back to the fundamental frequency of the carriersignal, as described in U.S. Pat. No. 9,515,815 at col. 10:61-13:4 andU.S. Pat. No. 9,338,042 at col. 6:30-8:4, both of which are incorporatedherein by reference. Using “harmonic TM modulation” techniques, forexample, TM modulator 208 can generate TM signals which represent X₃dimension coordinates of constellation symbols 302 by time or phaseshifts of the carrier harmonic.

As another example, in “internal TM modulation” techniques data can beencoded in time/phase shifts, amplitude shifts, or both time/phaseshifts and amplitude shifts of an internal TM signal, which can beapplied to the phase or the frequency of the carrier signal, asdescribed in U.S. patent application Ser. No. 15/491,569 at pp. 14-25and 31-33, which is incorporated herein by reference.

For example, in “internal TM modulation” the internal TM signal ischosen and modulated so as to be self-canceling within symbol periods ofthe non-TM signal with which it is combined, and preserves the featureof transparency with respect to the non-TM signal. The “internal TMsignal” can be applied to the carrier by adding the internal TM signalto the carrier' s phase or frequency.

Using “internal TM modulation” techniques, for example, TM modulator 208can generate TM signals which represent X₃ dimension coordinates ofconstellation symbols 302 by variations the location of time/phaseshifts, amplitude shifts, or both time/phase shifts and amplitude shiftsof the internal TM signal.

For example, as discussed in U.S. patent application Ser. No.15/491,569, internal TM modulation involves encoding data from an inputdata stream within discrete phase shifts, time shifts, or amplitudeshifts of an internal modulation signal (also referred to as an“internal TM signal” or simply the “TM signal” in reference to internalTM modulation). The internal TM signal is periodic signal, for example,a sinusoid or other periodic signal. The internal TM signal has afrequency that is related to the symbol frame (e.g., symbol period andsymbol rate) of a non-TM signal (e.g., a QAM signal) with which the TMsignal will be combined. For example, the internal TM signal can have afrequency that is an integer multiple of the symbol rate of the non-TMsignal.

For internal TM modulation, a TM modulator (e.g., TM modulator 208)modulates a carrier signal with the TM signal by applying the internalTM signal to the carrier signal. Internal TM modulation differs fromtraditional phase modulation in that the phase of the carrier signal isnot directly modulated or altered based on the input data signal.Instead, the internal TM signal is modulated with the data signal andthe entire sinusoidal internal TM signal is applied to the carrier by,for example, inserting the entire sinusoidal internal TM signal into thephase or frequency of the carrier signal. The data of the data signal isencoded in a phase, time shift, amplitude shift or a combination thereofof the internal TM signal and not directly in the carrier. Moreover,because the internal TM signal is periodic, variations in the phase ofthe carrier caused by the internal TM signal are averaged out over aninteger number cycles of the internal TM signal.

TM modulator 208 can add TM modulation to either the in-phase andquadrature-phase of the carrier signal that is received from the QAMmodulator 206. Signal combiner 214 combines the QAM and TM modulatedin-phase and quadrature-phase of the carrier signal passes the combinedsignal to the transmission amplifiers and antenna of the transmitter200.

Although illustrated as receiving the QAM modulated carrier signal fromQAM modulator 206, in some implementations, TM modulator 208 can beplaced before the QAM modulator 206 to modulate the carrier with the TMsignal first and then send the TM modulated carrier to the QAM modulator206.

Referring to FIGS. 2 and 3, in some implementations, constellation 300can be arranged as a set of two-dimensional QAM symbol constellations310. Symbols 302 in the QAM constellations 310 are represented byrespective modulation levels of the real portion of the QAM signal(QAM_({Re})) and imaginary portion of the QAM signal (QAM_({Im})).Constellation 300 can then include a plurality of layers oftwo-dimensional QAM symbol constellations 310, where each QAMconstellation layer 312 (e.g., the X₃ dimensions of constellation 300)is represented by a modulation value of a TM signal. For example, the 16symbols 302 in each 16-ary QAM constellation 310 can represent the 16binary values ranging from 0 (0000b) to 15 (1111b). In other, words theQAM constellations can remain constant in each layer 312. Moreover, tominimize bit errors, the bit patterns represented by each symbol in theQAM constellation 310 can be arranged according to a Gray code, suchthat each adjacent symbol differs by only one bit. The TM signal is usedto represent each QAM constellation layer 312 and, with four layers,permits an additional two bits to be appended to each symbol in the fullthree-dimensional constellation 300. By using the TM signal to representlayers 312 of QAM constellations Gray coding can be preserved evenbetween QAM constellation layers. For example, the first constellationlayer 312 (beginning from the front as showing in FIG. 3) may represent16 binary values ranging from 0 (00 0000b) to 15 (00 1111b); the secondconstellation layer 312 may represent 16 binary values ranging from 16(01 0000b) to 31 (01 1111b); the third constellation layer 312 mayrepresent 16 binary values ranging from 48 (11 0000b) to 63 (11 1111b);and the fourth constellation layer 312 may represent 16 binary valuesranging from 32 (10 0000b) to 47 (10 1111b), thereby preserving Graycoding between layers.

Constellation 300 can include N layers of M-ary QAM constellation layers312. For example, constellation 300 can include four layers of 16-QAMconstellations to produce a 64-ary three-dimensional constellation.Constellation 300 can include eight layers of 64-QAM constellations toproduce a 512-ary three-dimensional constellation. Constellation 300 caninclude sixteen layers of 256-QAM constellations to produce a 4096-arythree-dimensional constellation. In some implementations, for example,wired communication systems such as powerline Ethernet and coaxial cableor microwave backhaul systems, constellation 300 can include 32 layersof 1024-QAM constellations to produce a 32768-ary three-dimensionalconstellation.

Although illustrated as a square constellation, QAM constellation 310,and corresponding constellation layers 312 can be arranged in variousother shapes including, but not limited to rectangular and circularconstellations. For example, constellation 300 can include four layersof a circular 16-QAM constellation.

In some implementations, TM modulator 208 can add TM modulation to boththe in-phase and quadrature-phase of the carrier signal, according toone of the above TM modulation techniques. For example, TM modulator 208can generate a real (or in-phase) TM signal (TM_({Re})) and an imaginary(or quadrature-phase) TM signal (TM_({Im})), as described in U.S. Pat.No. 9,515,815 at col. 15:61-16:12, which is incorporated herein byreference. Symbol mapper 204 can map symbol coordinates for third andfourth dimensions of a four-dimensional symbol constellation to the real(TM_({Re})) and imaginary TM signals (TM_({Im})), respectively.

As discussed above and in U.S. patent application Ser. No. 15/491,569,“internal TM modulation” techniques can be used to carry information inboth phase shifts and amplitude shifts of a TM signal. Accordingly, insome implementations, for example, those using “internal TM modulation”techniques, symbol coordinates in a third and fourth dimension of asymbol constellation can be represented, respectively, by phase shiftvalues (TM_(φ)) and amplitude shift values (TM_(A)) of a single TMsignal.

In some implementations, two TM signals can be used to expand amulti-dimensional constellation to six dimensions. For example, symbolcoordinates in a third and fourth dimension of a symbol constellationcan be represented, respectively, by phase shift values and amplitudeshift values of a real TM signal (TM_(φ,{Re}) and TM_(A,{Re})) andsymbol coordinates in a fifth and sixth dimension of a symbolconstellation can be represented, respectively, by phase shift valuesand amplitude shift values of an imaginary TM signal (TM_(φ,{Im}) andTM_(A,{Im})) for a six-dimension constellation. In other words, TMsignals can be used to add an additional one to four dimensions to QAMsymbol constellations. For example, a 256-ary four-dimensionalconstellation can include four dimensions each with four coordinates. A65536-ary four-dimensional constellation can include four dimensionseach with sixteen coordinates. Similarly, a 4096-ary six-dimensionalconstellation can include six dimensions each with four coordinates.

In some implementations, multi-dimensional symbol constellations that donot represent an integer number of bits can be used. For example, a640-ary three-dimensional symbol constellation can be used. The 640-arythree-dimensional constellation can include two dimensions that eachhave eight coordinates (e.g., a 64-ary QAM constellation) and onedimension that includes ten coordinates (e.g., represented by modulationvalues of a TM signal). This constellation can only represent nine bitsof information (e.g., log₂(640)=9.322 bits). The constellation willinclude 128 extra symbols (e.g., 640−2⁹=128). These extra 128 symbolscan be reserved. For example, the extra 128 symbols can be used totransmit system information between transmitters and receivers. Each ofthe 128 symbols can represent 7-bits of system information. Moreover,when sending the system information using the reserved symbols, therewill be no need to send header information or other data to distinguishbetween data and system information because simply the use of thereserved symbols themselves will distinguish the data as being systeminformation.

In some implementations, symbol coordinates in two dimensions of athree-dimensional constellation can be represented by TM signals andsymbol coordinates in the third dimension can be represented by a non-TMsignal. For example, symbol coordinates in the first and seconddimensions of a constellation can be represented by any combinationTM_(φ,{Re}), TM_(A,{Re}), TM_(φ,{Im}), and TM_(A{Im}); and symbolcoordinates in the third dimension of the constellation can berepresented by a non-TM signal including, but not limited to, anamplitude modulated signal, a frequency modulated signal, or a phasemodulated signal.

FIG. 4 depicts a block diagram of an example signal receiver 400 inaccordance with implementations of the present disclosure. Receiver 400is a combined QAM-TM receiver. Receiver 400 can be implemented inhardware (e.g., as integrated circuits, chip-sets, application specificintegrated circuits (ASIC) or field programmable logic arrays (FPGA)) orin software (e.g., as a software defined radio (SDR)). Receiver 400includes a signal separator 402, a QAM demodulator 404, a TM demodulator406, and a symbol demapper 408. In addition, receiver 400, optionally,includes a decoder 410. Receiver 400 can also include various filtersand amplifiers (not shown) to properly process received signals.

Signal separator 402 receives the combined signal and separates the TMsignal. Signal separator 402 passes the TM signal to TM demodulator 406.In some implementations, signal separator 402 can send the combinedsignal directly to QAM demodulator 404 without further processingbecause the TM signal will be transparent to the QAM demodulator. Insome implementations, QAM demodulator 404 is a part of the signalseparator 402. For example, U.S. Pat. No. 9,338,042 at col. 12:18-13:38;14:14-53, which is incorporated herein by reference, describestechniques for separating TM signals from combined signals which employa non-TM signal demodulator (e.g., a QAM demodulator).

QAM demodulator 404 demodulates the QAM signal and passes correspondingsymbol coordinates for the dimensions X₁ and X₂ to symbol demapper 408.TM demodulator 406 demodulates the TM signal and passes correspondingcoordinates for dimension X₃ to symbol demapper 408. In implementationsthat use multiple TM signals (e.g., TM_(φ,{Re}), TM_(A,{Re}),TM_(φ,{Im}), and TM_(A,{Im})), TM demodulator demodulates the TM signalsand passes corresponding coordinates for dimensions X₃ to X_(N) tosymbol demapper 408.

TM demodulator 406 can be configured to perform TM demodulation using“wide-band TM modulation” techniques, “harmonic TM modulation”techniques, or “internal TM modulation” techniques, as appropriate. Forexample, “wide-band TM” demodulation techniques are described in U.S.Pat. No. 9,515,815 at col. 9:20-10:60, which is incorporated herein byreference. “Harmonic TM” demodulation techniques are described in U.S.Pat. No. 9,515,815 at col. 13:5-15:9 and U.S. Pat. No. 9,338,042 at col.10:66-11:44, both of which are incorporated herein by reference.“Internal TM” demodulation techniques are described in U.S. patentapplication Ser. No. 15/491,569 at pp. 25-31 and 33-34, which isincorporated herein by reference.

For example, as described in U.S. patent application Ser. No.15/491,569, for internal TM demodulation, a TM demodulator (e.g., TMdemodulator 406) receives a combined signal that includes a carriersignal modulated with both a TM signal and a non-TM signal (e.g., a QAMsignal). The TM demodulator demodulates or receives a demodulatedversion of the QAM signal. The TM demodulator uses the QAM symbol valuesof the demodulated QAM signal to remove the QAM modulation from thecombined signal, thereby, leaving only the TM signal. The TM demodulatorcan demodulate the TM signal by extracting the TM signal (e.g., theinternal TM modulation signal) from the phase of the carrier signal. TheTM demodulator identifies the TM symbols by detecting the discrete phaseshifts and/or amplitude shifts in the TM signal to demodulate the TMsignal. For example, TM receiver 106 can compare the TM signal to areference sinusoid to detect the phase shifts in the TM signal.

Symbol demapper 408 maps symbol coordinates to symbols in themulti-dimensional constellation and the corresponding bit patterns. Forexample, the demapper 408 maps the symbol coordinates to symbols and anN-bit binary number that corresponds to the symbol. Symbol demapper 408can output the remapped bits as a digital data stream.

Decoder 410 receives the demodulated and demapped data stream fromsymbol demapper 408. Decoder 410 decodes or decrypts any coding orencryption that was added to the data stream by encoder 202 oftransmitter 200. In some implementations, decoder 410 can detect orcorrect errors in the data stream using any error detection/correctioncodes applied to the data by encoder 202.

FIG. 5 depicts an example environment 500 for employing the techniquesdiscussed above. The example environment is described in the context ofcellular communication network (e.g., a cellular communication fronthaul network). It is appreciated, however, that implementations of thepresent disclosure can be realized in other appropriate environments andcontexts including, but not limited to, for example, computer networks,Internet of Things (IoT) networks, computer peripherals (e.g., plug andplay devices), device pairing, authentication protocols, near-fieldcommunications (NFC), inventory systems, broadcast and/or cablecastsystems, wired communication systems (e.g., Ethernet, USB), satellitecommunication systems, self-driving vehicles, autonomous vehiclecommunications (e.g., unmanned aerial vehicles (UAV)), traffic signalpreemption systems (e.g., used by emergency service vehicles), etc.

The environment 500 includes a base station 502 in communication withseveral mobile devices 504 and 506. The base station 502 can be a radiobase station (RBS) for a cellular communication system. The base station502 can include cellular transmitters, receivers, and computingequipment for processing cellular communications with the mobile devices504 and 506. In addition, the base station 502 is capable of conductingelectronic communications with TM modulated signals. For example, thebase station 502 can include QAM-TM transmitter(s) and QAM-TMreceiver(s) such as those described above in reference to FIGS. 2 and 4,respectively. It is appreciated, however, that in other contextscommunication devices such as a router, server, wireless access point,etc. could perform the operations similar to those described inreference to the base station 502.

The mobile devices 504 and 506 are associated with respective users 505and 507. The mobile devices 504 and 506 can each include various formsof a processing device including, but not limited to, a laptop computer,a tablet computer, a wearable computer, a handheld computer, a personaldigital assistant (PDA), a cellular telephone, a network appliance, asmart phone, an enhanced general packet radio service (EGPRS) mobilephone, a mobile hotspot, or an appropriate combination of any two ormore of these example communication devices or other communicationdevices. Furthermore, mobile devices 504 and 506 are capable ofconducting electronic communications with TM modulated signals. Forexample, the mobile devices 504 and 506 can each include a QAM-TMtransmitter and a QAM-TM receiver such as those described below inreference to FIGS. 2 and 4, respectively.

Moreover, QAM-TM transmitters and receivers can be configured to operatein a QAM only mode in which only QAM (or another non-TM modulation) isused, a TM only mode in which only TM modulation is used, or a QAM-TMmode in which both QAM and TM modulation are used. Furthermore, whenoperating in a QAM-TM mode, the QAM-TM transmitters and receivers cantransmit and receive data using multi-dimensional symbol constellationshaving three or more dimensions, as described above. In addition, QAM-TMtransmitters and receivers can expand and contract the symbolconstellation being used or to be used for communication in accordancewith conditions of a given communication channel, types or amounts ofdata being sent, or other appropriate conditions. In other words, thebase station 502 and mobile devices 504 and 506 can choose acommunication mode (e.g., QAM only, TM only, or QAM-TM) based onconditions including, but not limited to, received signal strength,channel error rate, type of data to be sent, amount of data sent, or acombination thereof.

For example, if particular types of data or an amount of data largerthan a predetermined size (“large amounts of data”) are beingtransmitted the base station 502 or mobile device 504 can use a QAM-TMconstellation 510 to transmit the particular type of data or the largeamount of data. For example, particular types of data that can triggerthe use of TM signals 142 can include, but are not limited to, datatypes that use significant portions of a channel bandwidth such asstreaming data (e.g., streaming video or audio), real time data (e.g.,video chat), analog data (e.g., analog direct current (DC) oralternating current (AC) signals), and data indicated as high priority(e.g., emergency notification data). However, if smaller amounts of dataare being transmitted, for example, the base station 502 or mobiledevice 506 can use a smaller QAM only or TM only constellation 512. Insome examples, low bandwidth data (e.g., SMS messages, text only e-mailmessages, etc.) may be prioritized for transmission using QAM or TM onlyconstellations 512.

In some implementations, the base station 502 and mobile devices 504 and506 can vary attributes of the multi-dimensional constellation to beused. For example, attributes such as number of dimensions andconstellation size can be chosen based on conditions including, but notlimited to, received signal strength, channel error rate, type of datato be sent, amount of data sent, or a combination thereof.

FIG. 6 depicts an example process 600 for encoding a communicationsignal in a multi-dimensional symbol constellation. Process 600 can beperformed by a transmitter such as transmitter 200 of FIG. 2. In someexamples, the example process 600 can be provided as computer-executableinstructions executed using one or more processing devices (e.g., adigital signal processor) or communication devices (e.g., base station502 or mobile devices 504 and 506 of FIG. 5). In some examples, theprocess 600 may be hardwired electrical circuitry, for example, as anASIC or an FPGA device. In some examples, the process 900 may beexecuted by an SDR.

A transmitter maps data from an input data stream to symbols of amulti-dimensional constellation that includes three or more dimensions(602). For example, bits of an input data stream are mapped to symbolsof the multi-dimensional constellation that represent corresponding bitpatterns. The symbols of the constellation can be represented by arespective set of coordinates including a first coordinate associatedwith a first signal, a second coordinate associated with a secondsignal, and a third coordinate associated with a third signal, where atleast one of the signals is a TM signal and at least one of the signalsis a non-TM signal. For example, the symbol coordinates of the firstdimension and second dimensions can be represented by respectivein-phase and quadrature phase modulation values of a QAM signal. Symbolcoordinates of the third dimension can be represented by a TM signal.

The transmitter modulates a carrier signal with the first, second, andthird signals (604). For example, the first and second signal can be ain-phase and quadrature-phases of a QAM signal and the third signal canbe a TM signal. The transmitter can then modulate the carrier with theQAM and TM signals.

In some implementation, the multi-dimensional symbol constellation canbe composed of a plurality of layers of two-dimensional QAMconstellations, where TM modulation levels represent particular QAMconstellation layers. For example, the multi-dimensional symbolconstellation can include at least four layers of 16-ary QAMconstellations. As another example, the multi-dimensional symbolconstellation can include at least eight layers of 256-ary QAMconstellations.

In some implementations, the third dimension of the multi-dimensionalsymbol constellation can be represented by phase values of the TMsignal, and a fourth dimension of the multi-dimensional symbolconstellation can be represented by amplitude values of the TM signal.

Some implementations include two TM signals where a first TM signal isapplied to an in-phase channel of a carrier signal and a second TMsignal is applied to a quadrature-phase channel of the carrier signal.Symbol coordinates for a third dimension of the multi-dimensionalconstellation can be represented by the first TM signal. Symbolcoordinates for a fourth dimension of the multi-dimensionalconstellation can be represented by the second TM signal. Thetransmitter can then modulate the in-phase part of the carrier signal awith the first TM signal, and the quadrature-phase part of the carriersignal with the second TM signal.

In some implementations, a transmitter can use a two-dimensional symbolconstellation where symbol coordinates in one dimension of theconstellation are represented by modulation values of a non-TM signaland symbol coordinates in the second dimension of the constellation arerepresented by modulation values of the TM signal. The non-TM signal canbe, for example, an amplitude modulation signal, a frequency modulationsignal (e.g., FSK), or a phase modulation signal (e.g., QPSK). Forexample, it may be advantageous in some communication channels or undersome channel conditions (e.g., noisy or channels with much multipathinterference) to use a lower dimensional constellation. Furthermore, insome channels or under some channel conditions a combination of a non-TMsignal with a TM signal may provide improved performance over a QAMsignal, thereby, permitting the use of a two-dimensional constellation,where the use of QAM would otherwise not be feasible.

In some implementations, a transmitter can use a two-dimensional symbolconstellation where symbol coordinates in both dimensions arerepresented by TM signal(s). For example, if an “internal TM modulation”technique is used, symbol coordinates in one dimension of theconstellation are represented by phase values of a TM signal and symbolcoordinates in the second dimension of the constellation are representedby amplitude values of the TM signal. In some implementations, symbolcoordinates in one dimension of the constellation can be represented bya first TM signal applied to an in-phase portion of a carrier signal andsymbol coordinates in the second dimension of the constellation can berepresented by a second TM signal applied to a quadrature-phase portionof the carrier signal. For example, it may be advantageous in somecommunication channels or under some channel conditions (e.g., noisychannels, channels with significant Doppler shifts, or channels withsignificant multipath interference) to use only TM signals. Forinstance, in some channels or under some channel conditions TM signalsmay provide improved performance over a QAM signal, thereby, permittingthe use of a two-dimensional constellation, where the use of QAM wouldotherwise not be feasible.

FIG. 7 depicts an example process 700 for decoding a communicationsignal from a multi-dimensional symbol constellation. Process 700 can beperformed by a receiver such as receiver 400 of FIG. 4. In someexamples, the example process 700 can be provided as computer-executableinstructions executed using one or more processing devices (e.g., adigital signal processor) or communication devices (e.g., base station502 or mobile devices 504 and 506 of FIG. 5). In some examples, theprocess 700 may be hardwired electrical circuitry, for example, as anASIC or an FPGA device. In some examples, the process 900 may beexecuted by an SDR.

A receiver receives a signal including a carrier signal modulated with aQAM signal and a TM signal, where the signal encodes data in amulti-dimensional symbol constellation that has at least threedimensions (702). The receiver separates the TM signal from the QAMsignal (704). The receiver demodulates the QAM signal to obtain firstand second coordinates of a data symbol and demodulates the TM signal toobtain a third coordinate of the data symbol (706). The receiver mapsthe first, second, and third coordinates of the data symbol to a patternof N-bits associated with the data symbol (708).

Implementations of the subject matter and the operations described inthis specification can be realized in analog or digital electroniccircuitry, or in computer software, firmware, or hardware, including thestructures disclosed in this specification and their structuralequivalents, or in combinations of one or more of them. Implementationsof the subject matter described in this specification can be realizedusing one or more computer programs, i.e., one or more modules ofcomputer program instructions, encoded on computer storage medium forexecution by, or to control the operation of, data processing apparatus.Alternatively or in addition, the program instructions can be encoded onan artificially generated propagated signal, e.g., a machine-generatedelectrical, optical, or electromagnetic signal that is generated toencode information for transmission to suitable receiver apparatus forexecution by a data processing apparatus. A computer storage medium canbe, or be included in, a computer-readable storage device, acomputer-readable storage substrate, a random or serial access memoryarray or device, or a combination of one or more of them. Moreover,while a computer storage medium is not a propagated signal; a computerstorage medium can be a source or destination of computer programinstructions encoded in an artificially generated propagated signal. Thecomputer storage medium can also be, or be included in, one or moreseparate physical components or media (e.g., multiple CDs, disks, orother storage devices).

The operations described in this specification can be implemented asoperations performed by a data processing apparatus on data stored onone or more computer-readable storage devices or received from othersources.

The term “data processing apparatus” encompasses all kinds of apparatus,devices, and machines for processing data, including by way of example aprogrammable processor, a computer, a system on a chip, or multipleones, or combinations, of the foregoing. The apparatus can includespecial purpose logic circuitry, e.g., an FPGA (field programmable gatearray) or an ASIC (application specific integrated circuit). Theapparatus can also include, in addition to hardware, code that createsan execution environment for the computer program in question, e.g.,code that constitutes processor firmware, a protocol stack, a databasemanagement system, an operating system, a cross-platform runtimeenvironment, a virtual machine, or a combination of one or more of them.The apparatus and execution environment can realize various differentcomputing model infrastructures, such as web services, distributedcomputing and grid computing infrastructures.

A computer program (also known as a program, software, softwareapplication, script, or code) can be written in any form of programminglanguage, including compiled or interpreted languages, declarative orprocedural languages, and it can be deployed in any form, including as astand-alone program or as a module, component, subroutine, object, orother unit suitable for use in a computing environment. A computerprogram can, but need not, correspond to a file in a file system. Aprogram can be stored in a portion of a file that holds other programsor data (e.g., one or more scripts stored in a markup languagedocument), in a single file dedicated to the program in question, or inmultiple coordinated files (e.g., files that store one or more modules,sub programs, or portions of code). A computer program can be deployedto be executed on one computer or on multiple computers that are locatedat one site or distributed across multiple sites and interconnected by acommunication network.

Communication devices can be configured to perform the processes andlogic flows described in this specification. For example, communicationdevices can include installed hardware, firmware, and/or software which,when the software is executed by the hardware, the above describedprocesses and logic flows are performed. For example, communicationdevices can include one or more programmable processors executing one ormore computer programs to perform the processes and logic flowsdescribed in this specification. The processes and logic flows can alsobe performed by, and apparatus can also be implemented as, specialpurpose logic circuitry, e.g., an FPGA (field programmable gate array)or an ASIC (application specific integrated circuit). For example,communication devices can include special purpose logic circuitry, e.g.,an FPGA (field programmable gate array) or an ASIC (application specificintegrated circuit) that is configured or programed to perform theprocesses and logic flows described in this specification.

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read only memory ora random access memory or both. Elements of a computer can include aprocessor for performing actions in accordance with instructions and oneor more memory devices for storing instructions and data. Moreover, acomputer can be embedded in another device, e.g., a mobile telephone, apersonal digital assistant (PDA), a mobile audio or video player, a gameconsole, a Global Positioning System (GPS) receiver, or a portablestorage device (e.g., a universal serial bus (USB) flash drive), to namejust a few. Devices suitable for storing computer program instructionsand data include all forms of non-volatile memory, media and memorydevices, including by way of example semiconductor memory devices, e.g.,EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internalhard disks or removable disks; magneto optical disks; and CD ROM andDVD-ROM disks. The processor and the memory can be supplemented by, orincorporated in, special purpose logic circuitry.

While this specification contains many specific implementation details,these should not be construed as limitations on the scope of anyimplementation of the present disclosure or of what can be claimed, butrather as descriptions of features specific to example implementations.Certain features that are described in this specification in the contextof separate implementations can also be implemented in combination in asingle implementation. Conversely, various features that are describedin the context of a single implementation can also be implemented inmultiple implementations separately or in any suitable sub-combination.Moreover, although features can be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination can be directed to asub-combination or variation of a sub-combination.

Similarly, while operations are depicted in the drawings in a particularorder, this should not be understood as requiring that such operationsbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. In certain circumstances, multitasking and parallel processingcan be advantageous. Moreover, the separation of various systemcomponents in the implementations described above should not beunderstood as requiring such separation in all implementations, and itshould be understood that the described program components and systemscan generally be integrated together in a single software product orpackaged into multiple software products.

Thus, particular implementations of the subject matter have beendescribed. Other implementations are within the scope of the followingclaims. In some cases, the actions recited in the claims can beperformed in a different order and still achieve desirable results. Inaddition, the processes depicted in the accompanying figures do notnecessarily require the particular order shown, or sequential order, toachieve desirable results. In certain implementations, multitasking andparallel processing can be advantageous.

What is claimed is:
 1. A transmitter comprising: at least one processor;and a data store coupled to the at least one processor havinginstructions stored thereon which, when executed by the at least oneprocessor, causes the at least one processor to perform operationscomprising: mapping data to symbols of a multi-dimensional symbolconstellation comprising at least three dimensions, each dimension ofthe constellation represented by a respective modulation signal, thedimensions including: first and second dimensions each of which arerepresented by respective in-phase modulation values and quadraturephase modulation values of a quadrature amplitude modulation (QAM)signal, and a third dimension represented by phase values of atranspositional modulation (TM) signal; and modulating a carrier signalwith the TM signal and the QAM signal.
 2. The transmitter of claim 1,wherein the TM signal is a first TM signal, wherein the carrier signalincludes an in-phase portion and a quadrature-phase portion, and whereina fourth dimension of the multi-dimensional symbol constellation isrepresented by a second TM signal, and wherein modulating the carriersignal with the TM signal comprises: modulating the one of the in-phaseportion of the carrier signal with one of the first TM signal or thesecond TM signal, and modulating the quadrature-phase portion of thecarrier signal with the other one of the first TM signal or the secondTM signal.
 3. The transmitter of claim 1, wherein a fourth dimension ofthe multi-dimensional symbol constellation is represented by amplitudevalues of the TM signal.
 4. The transmitter of claim 1, wherein themulti-dimensional symbol constellation comprises a plurality of layersof two-dimensional QAM constellations and modulation values of the TMsignal represent particular QAM constellation layers.
 5. The transmitterof claim 4, wherein the multi-dimensional symbol constellation comprisesat least four layers of 16-ary QAM constellations.
 6. The transmitter ofclaim 4, wherein the multi-dimensional symbol constellation comprises atleast eight layers of 256-ary QAM constellations.
 7. The transmitter ofclaim 1, wherein adjacent symbols in the multi-dimensional constellationare encoded using Gray coding.
 8. The transmitter of claim 1, whereinthe operations further comprise encoding the data using an errorcorrection coding scheme before mapping the data to symbols of themulti-dimensional constellation.
 9. A transmitter comprising: at leastone processor; and a data store coupled to the at least one processorhaving instructions stored thereon which, when executed by the at leastone processor, causes the at least one processor to perform operationscomprising: mapping bits of an input data stream to symbols of amulti-dimensional symbol constellation comprising at least threedimensions, symbol coordinates in two of the at least three dimensionsrepresented by in-phase and quadrature phase coordinates of a quadratureamplitude modulation (QAM) constellation and symbol coordinates in athird dimension represented by a phase value of a transpositionalmodulation (TM) signal; and modulating a carrier signal with the TMsignal and with the in-phase and quadrature phase coordinates of the QAMsignal.
 10. The transmitter of claim 9, wherein the multi-dimensionalconstellation comprises four dimensions, and wherein the respective setsof coordinates each further include a fourth coordinate associated withan amplitude value of the TM signal.
 11. The transmitter of claim 9,wherein the multi-dimensional symbol constellation comprises a pluralityof layers of two-dimensional QAM constellations and modulation values ofthe TM signal represent particular QAM constellation layers.
 12. Thetransmitter of claim 9 wherein the operations further comprise encodingthe data using an error correction coding scheme before mapping the datato symbols of the multi-dimensional constellation.
 13. A transmittercomprising: at least one processor; and a data store coupled to the atleast one processor having instructions stored thereon which, whenexecuted by the at least one processor, causes the at least oneprocessor to perform operations comprising: mapping data to symbols of amulti-dimensional symbol constellation comprising at least threedimensions, each dimension of the constellation represented by arespective modulation signal, the dimensions including: first and seconddimensions each of which are represented by respective in-phasemodulation values and quadrature phase modulation values of a quadratureamplitude modulation (QAM) signal, and a third dimension represented byamplitude values of a transpositional modulation (TM) signal; andmodulating a carrier signal with the TM signal and the QAM signal. 14.The transmitter of claim 13, wherein a fourth dimension of themulti-dimensional symbol constellation is represented by phase values ofthe TM signal.
 15. The transmitter of claim 13, wherein themulti-dimensional symbol constellation comprises a plurality of layersof two-dimensional QAM constellations and modulation values of the TMsignal represent particular QAM constellation layers.
 16. Thetransmitter of claim 15, wherein the multi-dimensional symbolconstellation comprises at least four layers of 16-ary QAMconstellations.
 17. The transmitter of claim 13, wherein adjacentsymbols in the multi-dimensional constellation are encoded using Graycoding.
 18. The transmitter of claim 13, wherein the operations furthercomprise encoding the data using an error correction coding schemebefore mapping the data to symbols of the multi-dimensionalconstellation.
 19. A transmitter comprising: at least one processor; anda data store coupled to the at least one processor having instructionsstored thereon which, when executed by the at least one processor,causes the at least one processor to perform operations comprising:mapping bits of an input data stream to symbols of a multi-dimensionalsymbol constellation comprising at least three dimensions, symbolcoordinates in two of the at least three dimensions represented byin-phase and quadrature phase coordinates of a quadrature amplitudemodulation (QAM) constellation and symbol coordinates in a thirddimension represented by an amplitude value of a transpositionalmodulation (TM) signal; and modulating a carrier signal with the TMsignal and with the in-phase and quadrature phase coordinates of the QAMsignal.
 20. The transmitter of claim 19, wherein the multi-dimensionalconstellation comprises four dimensions, and wherein the respective setsof coordinates each further include a fourth coordinate associated witha phase value of the TM signal.
 21. The transmitter of claim 19, whereinthe multi-dimensional symbol constellation comprises a plurality oflayers of two-dimensional QAM constellations and modulation values ofthe TM signal represent particular QAM constellation layers.
 22. Thetransmitter of claim 19, wherein the operations further compriseencoding the data using an error correction coding scheme before mappingthe data to symbols of the multi-dimensional constellation.